Ventral Intermediate Nucleus of the Thalamus versus Posterior Subthalamic Area: Network Meta-Analysis of DBS Target Site Efficacy for Essential Tremor

Abstract

<b><i>Background:</i></b> Deep brain stimulation (DBS) targeting the ventral intermediate nucleus (Vim) of the thalamus or the posterior subthalamic area (PSA) are effective treatments for essential tremor (ET). However, their relative efficacy is unknown. <b><i>Objective:</i></b> Here, we present the first systematic review and network meta-analysis, examining the efficacy of Vim versus PSA DBS for treating medically refractory ET. <b><i>Methods:</i></b> We included all primary studies that reported validated Fahn-Tolosa-Marin Tremor Rating Scale (FTM-TRS) scores pre-/postimplantation or on-/off-stimulation postimplantation, for patients receiving either Vim or PSA DBS. The primary outcome was FTM-TRS score reduction; the secondary outcome was percent reduction in score. We categorized all outcomes as short-term (≤12 months) or long-term (>12 months). <b><i>Results:</i></b> For pre-/postimplantation comparisons, 19 and 11 studies met inclusion criteria for short- and long-term follow-ups, respectively. For on-/off-stimulation tremor score comparisons, 8 studies met inclusion criteria for short-term follow-up. Network meta-analysis of pre-/postimplantation tremor scores showed greater tremor reduction with PSA implantation short-term (absolute tremor reduction: PSA: −30.94 [95% confidence interval (CI): −34.93, −26.95]; Vim: −26.26 [95% CI: −33.39, −19.12]; relative tremor reduction: PSA: 63.3% [95% CI: 61.8%–64.8%]; Vim: 57.8% [95% CI: 56.5%–59.0%]). However, there was no difference in efficacy between PSA and Vim DBS when comparing tremor on-versus off-stimulation at short-term follow-up or pre- versus postimplantation tremor reduction long-term. <b><i>Conclusion:</i></b> Our systematic review highlighted both heterogeneity in scoring systems used and lack of transparency in reporting total scores, limiting direct comparison across studies. We found a modestly superior efficacy with PSA stimulation in the short term, but no difference in tremor reduction long-term.

Unilateral Magnetic Resonance Imaging–Guided Laser Interstitial Thermal Therapy Thalamotomy for Essential Tremor

“…In this retrospective, single‐center, single‐blinded pilot study of 9 patients, unilateral thalamotomy with MRIg‐LITT had an acceptable profile of AEs and led to improvement in tremor and QOL of patients with medically intractable ET. We successfully targeted and ablated the VIM nucleus of the thalamus, resulting in expected clinical outcomes that are comparable to those seen with RF, GKRS, and MRIg‐FUS thalamotomies 9,10,23 . In our study, we observed an 83.37% reduction in tremor at 12 months, compared to 74% to 90% for RF thalamotomy, 48% to 63% for GKRS thalamotomy, and 35% to 75% for MRIg‐FUS thalamotomy reported in a literature review 23 .…”

“…Deep brain stimulation (DBS) of the VIM nucleus is an effective therapy for medically intractable ET but may not be an option for many patients due to various sociomedical reasons or specific contraindications (patient preferences, cost implications, and follow‐up requirements; the necessity for ongoing magnetic resonance imaging [MRI] surveillance of existing cerebral pathologies; challenges faced by patients already equipped with cardiac pacemakers; and the unique demands of individuals engaged in certain professions or sports) 7,8 . Alternative lesional brain surgery procedures, such as thalamotomy using radiofrequency (RF), gamma‐knife radiosurgery (GKRS), or magnetic resonance imaging–guided focused ultrasound (MRIg‐FUS), have been shown to be efficacious to manage tremor symptoms in individuals for whom DBS is unsuitable 5,9,10 …”

Posterior subthalamic area deep brain stimulation for recurrent tremor after ventral intermediate nucleus thalamotomy: a case report

“…However, a randomized, double-blind, crossover trial by Barbe et al [18] identified that PSA DBS is equally effective and more efficient than VIM DBS after 1-year-use. A recent meta-analysis also demonstrated modest superior efficacy of PSA stimulation for treating refractory ET in the short-term follow-up [19]. In addition, simultaneous targeting of VIM and PSA via one trajectory is possible because simply advancing the electrode more deeply from VIM can reach the PSA accurately [20].…”

A Systematic Review Comparing Focused Ultrasound Surgery With Radiosurgery for Essential Tremor

“…independently screened all titles and abstracts based on the following inclusion and exclusion criteria. 16 The inclusion criteria were (1) the study population comprised patients with only ET, (2) the patients received either unilateral SRS-T or FUS-T, and (3) tremor severity in the study was scored using a validated tremor scoring scale. Exclusion criteria were (1) all articles not available in English; (2) studies that involved animals, without any human participants; (3) technical analyses; (4) editorials; (5) literature or systematic reviews; (6) case reports or series with <5 patients; and (7) follow-up ≤3 months (Figure 1).…”